[SalesForce] Get Selected Picklist Value

I've been trying to insert a custom setting record wherein role name selected from the dropdown menu must be the saved value in the Role_Name__c field. But every time record is inserted, role name does not have any value.

Apex Class:

public class SettingController {

    public WrapperSetting wrapSet {get; set;}
    public String selectedRoleValue {get;set;}

    public SettingController() {
        String wrapSetId = ApexPages.currentPage().getParameters().get( 'id' );

        if (wrapSetId != null ) {
            wrapSet = new WrapperSetting([SELECT Id, Name, TextField__c, Role_Name__c FROM Setting__c WHERE Id = :wrapSetId]);
        } else {
            wrapSet = new WrapperSetting();
        }
    }

    public List<SelectOption> getUserRoleList() {
        List<UserRole> userRoleList = [SELECT Id, Name FROM UserRole];
        List<SelectOption> uRoleOptionList = new List<SelectOption>();
        uRoleOptionList.add(new SelectOption(' ',' '));

        for(UserRole ur : userRoleList) {
            uRoleOptionList.add(new SelectOption(ur.Id, ur.Name));    
        }

        return uRoleOptionList;
    }


    public PageReference save() {
        if (wrapSet.Id != null) {
            update wrapSet.getSetting();
        } else {
            wrapSet.insertSetting();
        }

        PageReference pr = new PageReference('/' + wrapSet.Id);
        pr.setRedirect(true);
        return pr;
    }

    public class WrapperSetting {
        public Id Id {get;set;}
        public String Name {get;set;}
        public String TextField {get;set;}
        public String selectedRole {get;set;}

        public WrapperSetting(Setting__c s2) {
            this.Id = s2.Id;
            this.Name = s2.Name;
            this.TextField = s2.TextField__c;
            this.selectedRole = s2.Role_Name__c;

        }

        public WrapperSetting() {}

        public Setting__c getSetting() {
            return new Setting__c(
                Id = this.Id,
                Name = this.Name,
                TextField__c = this.TextField, 
                Role_Name__c = this.selectedRole

            );
        }

        public void insertSetting() {
            Setting__c s = this.getSetting();
            insert s;
            this.Id = s.Id;
        }

    }
}

Visualforce Page:

<apex:page controller="SettingController" sidebar="false" showHeader="false">
    <apex:pageMessages />
    <apex:form >
        <apex:pageBlock >
            <apex:pageBlockSection >
                <apex:pageBlockSectionItem >
                    <apex:outputLabel >Name</apex:outputLabel>
                    <apex:inputText value="{!wrapSet.Name}"/>                
                </apex:pageBlockSectionItem>
                <apex:pageBlockSectionItem >
                    <apex:outputLabel >Text Field</apex:outputLabel>
                    <apex:inputText value="{!wrapSet.TextField}"/>                
                </apex:pageBlockSectionItem>
                <apex:pageBlockSectionItem >
                    <apex:outputLabel >Role Name</apex:outputLabel>
                    <apex:selectList value="{!selectedRoleValue}" size="1">
                        <apex:selectOptions value="{!UserRoleList}"/> 
                    </apex:selectList>                
                </apex:pageBlockSectionItem>
            </apex:pageBlockSection>
            <apex:pageBlockButtons >
                <apex:commandButton action="{!save}" value="Save" />
            </apex:pageBlockButtons>
        </apex:pageBlock>
    </apex:form>
</apex:page>